Mechanical pencil



Sept. 2, 1930. R, CHELTON El AL MECHANICAL PENG IL Filed Feb. 14. 1927 www A l www J? 7 Patented 2,: f

. v IJNVITED STATES PATENT oFFIcE tion which shall w ed to utilize al somewhat ttl lill

nomma casaron, or cmcaeo,

missions, or cmcaeo,

AND CHARLES IB. IEEBAN, O EVANSTON, LLINOIS, BY HEERE ASSIGNMENTS, '1120V MANUFACTURING COMPANY,

ILLINOIS, A coRroBA'rIoN or minors j imcnANrcAL menu Application lcd'lebruary 14, 192i. Serial No. 167,923.

` This invention relates to mechanical pencils and its obj ect is to provide a construcbe economical to manufacand which is adaptlonger lead than most constructions now in commercial use. The invention consistsin certain features and elements in combination, as hereinshown and described and as indicated by the claims. ln the drawings: Figure 1 is an axial sectionoi a pencil ernbodying this invention. Figure 2 is a parti l axial section of the saine on a larger scale.

ligure 3 is a transverse section taken as indicated at line, 3--3, on Figure 1.

Figure d is a transverse section talren asindicated at. line, l-l on Figure l.

Figure 5 is a detail view of the lead-propelling plunger,s

Figure d is a detail view ci the plunger talren at right angles to the vView of Figure 5. Figure is an end the plunger..

view or liigure 8 is an axial section ci: a modified 'ture and simple to repair,

i'orrn o-E the pencil..

Figure 9 is a transverse section taken asindicated at line, 9--9, on Figure 8.

As shown in Figure 'l the structure includes a barrel, i, which is preferably ornamental in character and may be composed o Celluloid, of balrelite, hard rubber or other composition, and which is tted at its upper end with a tubular metallic ierrule, 2, reduced to receive a cap, 3, which encloses an eraser rubber, l, and its holder, 5. Said holder, 5, serves as a closure 'for theupperend portion. of the barrel which may be used as a container for spare leads indicated at 6. Preferably a lining tube, 7, is inserted in this upper end portion to form a shoulder against which a partition member, 8, is entered Jfrom the opposite -end oi? the barrel, 1.

The lead-propelling mechanism is operated by rotation et the tapered tip member, 9, which may be split at 9a, for a short distance back from its smaller end to furnish trictional guidance for the lead, 10, in use. ller, 11, secured near the smaller end of the tip, 9, is formed with a bore substantially itting the lead, 10, and in the upper end of said `filler there is anchored the propelling screw which is in the form of an open spiral,

12, constructed from a-flat metal 'ribbon helif 12, between adjacent callycoiled with spaces, coils. A lunger, 13, is loosely slidable in the helical co1 12, and is provided projectmgllugs or wings, 13, which extend radially t rough the spaces, 12B, and project beyond the outer diameter of the coil, 12. The projecting ends of the lugs, 138, are engaged in longitudinal guide vgrooves of a stationary guide tube, 14, and said grooves are preferably formed by making the tube, 1d, of corrugatedv cross-section with corrugations diametrically disposed, as indicated in Figure 3. If desired this may be accomplished by a swaging 'or' rolling process ap'- plied to a'tubeoi' initially circular cross section and preferably the tube is formed with four corrugations disposed in pairs at right angles to each other so that its external forni may be circumscribed by a square and the tube, 14, will be held against rotation when inserted into such circumscribed square. The lower end oi the guide tube,'14, is permanently secured 1n a bushing, 15, tapered at one end to conform tothe taper of the outer tip,

9, and having a cylindrical portion, which abuts against the end of the barrel, 1 with a reduced portion, 15b, which is inserted snugly intothe bore of the barrel, 1, as seen in Figures 1 and 2. rlhe inner diameter ci the part, 15", and the inner diameter of the tapered end portion at its extreme end are substantially equal to that of the circle which will just -circumscribe the corrugated guide tube, 14, so that the tube is snugly centered in the bushing, 15', andl may be permanently fixed therein by the application of a small Y amount of solder in the bore of the reduced part, 15b. The bushing, 15, is flanged over at its smaller end as seen at 15, forming a stop against which the corrugated tube, 14, is inserted. This assembly of the corrugated tube, 14, and the bushing, 15, thus constitutes a guide unit upon which the tip, 9, is rotatably mounted and which is itself fixed to the barrel, 1, by frictional engagement of the part, 15", in the bore of the barrel. Preferably this engagement is rendered more posilco the coil to insure long wear an tive by making a artition member, 8, in the from of a cup wit side walls, 8, swagedto circumscrihe the square form of the .gulde tube, 14, so as to hold it againstrptation as indicated in Figure 4,-the partltlon, 8, being a comparatively tight t in the barrel, 1, and being forced to its position thereln.

When the parts are thus assembled, 1t will be seen that the plunger, 13, while freely slidable in axial direction, will beheld against rotation by engagement of its lugs, 13", m the grooves of the corrugated tube, 14, but that rotation of the tip, 9, on the bushing, 15.

will turn the coil, 12, so as to cause the helical groove formed by the s ace, 12, to feed the lugs, 13, up or down or advancing or retracting the lead-propelling plunger, 13.

The plunger, 13, is convemently made from fiat sheet stock initially blanked out with the lugs, 13, projecting from its stem portion. In a second operation a forming die will give a stem a substantially circular cross section and produce beveled surfaces, 13", on the lu s, 13, which are inclined to correspond with the pitch of the helical coil, 12, thus providing substantial surfaces for engagement with easy operation.

For still greater economy of manufacture the bushing member, 15, may be dispensed with, as indicated in Figures 8 and 9. In this arrangement the barrel, 20, has a tapered terminal portion, 20, fitting into the tapered tip, 9, and Within this portion a reduced bore is formed to substantially tit the outer diameter of the coil, 12. From the shoulder, 20", which results from the reduced bore, the larger bore of the barrel, 20, is squared at 20, for a short distance for non-rotative engagement withthe corrugated guide tube,' 14, which in this instance is inserted into the barrel from the upper end. A partition may be formed by closing over `the end of the tube, 14 at 14", thus dispensing with any separate member for this purpose. At its lower end portion the helical coil, v12, is wound at a dierent pitch so as to leave no space between its adjacent coils, and thus forms a.

substantially closed 'tube which is anchored directly in the tip, 9, and centered therein by a bushing, 21. The plunger, 13, is of thel same construction as already described and the structure at the upper end including the eraser, 4, and cap, 3, may be exactly like that shown in Figure 1.

We claim 1. In a mechanical pencil. a barrel, a bushing inserted in the bore of the barrel at one end, a guide tube fixed in the bushing and Vextending into the barrel, with means holding the tube against rotation in the barrel, a tapered tip having a bore for a pencil lead at its smaller end and supporting one end of coiled helix whose opposite end is d extends into the guide tube, to-

ether with a lunger in the coil ha aterally extending lugs projecting throvli the spaces of the coil :for longitudinal sliding engagement with the guide tube, said lu being disengageable from the helix throu its open end and means at the lower end of t e guide tube for retaining the plunger by engagement with said lugs.

2. In a mechanical pencil, a barrel and a guide tube therein, a lead-propelling plunger slidable longitudinally in the guide 4tube and holding means comprising a cup fitted tightly into the barrel, the cup being non-circular in cross section, and the guide tube having a nonilcircular cross section interlocked therewit 3. In a mechanical pencil, a barrel, a bushing having a reduced end portion inserted in the bore of the barrel, said bushing being formed of relatively thin stock tapered toward its opposite end, a guide tube which is corru ated in cross-section itted in said bushing, t e inner` diameter of the tapered end lof the bushing and the inner diameter of the reduced end of the bushing being substantially equal and circumscribing .the corrugated tube, said tapered end of the bushing having an in-turned flange Whose diameter is that of the inscribed circle of the corrugated tube, a helical coil rotatable in said tube and a plunger in said coil having lugs projecting laterally through the spaces between adJacent turns ofthe coil for engaging the longitudinal grooves of the corrugated tube, together with an outer tip member for the pencil rotatable on the bushing and operatively engaging the outer end of the coil for turning it, said tip having a lead guide and bore at its outer end.

4. In a mechanical pencil, a barrel, a lining tube extending within said barrel through a part of its length, a partition cup in the barrel at the inner end of said lining tube, a guide tube extending through the remainder of the barrel from said cup and protruding from the end of the barrel, a bushing in which the protruding end of said guide tube is secured, said bushing having a reduced portion inserted in the bore of the barrel, the opposite end of the bushing being tapered, a tapered shell fitted rotatably over said bushing and a helical coil fixed in the outer end of said shell and extending into the guide tube, together with a plunger slidable in said coil and having laterally projecting lugs extending through the spaces between the turns of the coil for engagement Wirth longitudinal guideways in the guide tu e.

5. In a mechanical pencil, a barrel, a lining tube extending therein through a part of its length, a partition in the iorm of a cup with its bottom Wall abutting said lining tube, the side walls of the cup 'forming c, chamber oi non-circular cross section,

lill@ EIM ' ofthe coil for engaging the channels of the a guide tube occupying the remainder of the barrel' corrugate 'to provide longitudinal grooves internally for engagement with a lead-propelling nally therein, a non-circular form which is locked a ainst rotation by insertion in the cup-shape partition.

6. In a mechanical pencil, a barrel, a guide tube which is corru ated in cross section to uide tube, said guide tube being anchored 1n the barrel to hold it against rotation.

In testimony whereof, we have hereunto set our hands, this 12th day of J anua 1927.

ROBERT CHELTO' CHARLES R. KEERAN.

plunger slidable longitudir sa1d tube externallyl presenting 

